DETERMINING PROPER AXLE HUB FACE ACCORDING TO TRAILER BOX WIDTH
Begin by measuring the box width(A) of the trailer. Technically the overhang(B) is measured from the center of the spring hanger, but for the sake of simplifying this process we will measure from the outside edge of the box. Below is a table giving acceptable limits of overhang (I have subtracted the difference of the overhang out of the table) for different sizes and styles of axles. Add box width(A) to the (minimum and maximum individually to get a range) overhang(B) and you get the (acceptable range of) axle hub face(C) for the box size of your trailer. Be sure to also take into account fenders and offset of wheel/tire combos when narrowing it down to the hub face that fits you needs. It is smart to figure approximately 1.5"+ clearance between your tires and trailer box and/or fender backs to allow for margin of error.
Tubular Straight (TS) / Tubular Drop (TD)
| Axle Type | Minimum | Maximum |
| TS2000 | 9" | 17" |
| TS3500 | 11" | 17" |
| TD3500 | 13" | 17" |
| TS5200 | 12" | 16" |
| TD5200 | 14" | 18" |
| TS6000 | 12" | 16" |
| TD6000 | 14" | 18" |
| TS7000 | 12" | 18" |
| TD7000 | 14" | 19" |
| TS8000 | 15" | 19" |
| TD8000 | 16" | 19" |
| 9000 | 25" | 32" |
| 12000 | 25" | 32" |
Torsion Axles (EQ)
| Axle Type | Minimum | Maximum |
| EQ2000 | 12.5" | 22" |
| EQ3500 | 12.5" | 24" |
| EQ6000 | 14.5" | 24" |
| EQ7000 | 14.5" | 28" |
| EQ8000 | 17.5" | 43" |
